The membrane attack complex of complement causes much of complement mediated tissue damage. Its production is associated with the formation of neoantigens which can be used to identify it. A new high yield purification procedure for SC5b-9 was developed. Fresh human serum was activated with zymosan. The SC5b-9 complex was purified by precipitation with polyethylene glycol, affinity purification on anti-C5 sepharose and molecular seive chromatography. The yield from this procedure was 6-10 fold higher than previously reported. Polyclonal antibodies to SC5b-9 neoantigens were prepared in goats. Generation and characterization of monoclonal antibodies to these neoantigens is currently in progress. In the second phase of this project, high yield purification of C9 was accomplished by DEAE and hydroxylapatite ion-exchange chromatography and anticontaminant affinity column chromatography. Hydrophobic and hydrophilic fragments of C9 will be produced by Alpha-thrombin cleavage, and monoclonal and polyclonal antibodies to these fragments will be produced. The antibodies to SC5b-9 neoantigens and C9 fragments will be used to study C5b-9 deposition in human tissues from patients with certain auto-immune disorders. C5b-9 orientation and localization in mammalian and bacterial membranes will also be studied.